Method of drilling wells



" WITNESSES W. E. NOLAN.

MEHopoF omLLlNG WELLS'. APPLICATION FILED MAR. 3l, 1920.

1,401,488, Patented m0211921.'

'V1/ Sang/@fone ATTORNEY UNlrEo .sTATEs' PATENT OFFICE-.

WILLIAM EfNoLAN, or TULSA, OKLAHOMA.

METHOD OF DRILLING'WELLS.

Specification of Letters Patent. 4:Patnted Dec. 27, 1921,

Application led March 31, 1920. Serial No. 370,226.

To ali/whom# my concern Be it known that I, WILLIAM E.` NoLAN, a citizen of .the United States, res-iding at 'Tulsa, in the county of Tulsa and Stateof Oklahoma, have invented a new and useful Method of Drilling Wells, of which the following is a specification. y

This invention has reference to a method y of drilling wells, and more particularly oil wells, and its object is to provide for the drilling of wells without simultaneously casi ing them, whereby the cost `of drilling is A typical formation may consist of a sury face layer under which is capi rock covering water-charged sand stone, andy such sand stone covers a layer or layers of caving shale which may cover a layer of cap rock overlying gas sand stone, in turn covering oil sand stone.

Such a formation varies considerably in different localities. Sometimes the oil is found near the surface and again several thousand feed deep. Usually gas sand and oil-bearing 'sand` covered by cap rock, such` as limestone, occurs three or -four thousand feet down' with hundreds or thousands of which is of unstable nature, water-containing sand stone is found held from the water escaping by limestone or similar cap rock found a few score feet below the surface of the ground. -V In drilling a test bore 4which may subsequently become the rmanent bore a cellar excavation fifty or slXty feetvdeep or thereabout is formed down to the cap rock,. and fromthe bottom of the cellar a bore is start# ed, such bore being of suitable diameter to accommodate a casing six or eight inches, or somewhat larger, in diameter. The bottom of the cellaris provided with a heavy coat'- feet of shaleoverlying it, and upon the shale,V

ing of cement through which-the casing is carried and, entering the casing above the bottom or sealing layer is a pipe permit-` ting the introduction of air under pressure. vHaving made the necessary preliminary preparations the boring then proceeds and may continue through various strata untilultimately the oil sand is` reached. "The drill, 1n its course, passes through waterbearing" strata, caving'shale, impervious cap rock andfinally reaches gassand anduoilbearing sand. It has heretofore been found necessary to provide casing to keep out the water and to prevent the caving shale from fillmg up the' bore, which materials vfrequently clog the well and prevent it from producing.

In drilling a well the use of air pressure for holdingl back the water and caving shale avoids Vthe necessity of usingl casing for a like purpose and also eliminates many troubles which have been met by oil well drillers 'and 'the heavy preliminary costs and fre#A quent mishaps which have to be met.

The invention will be best understoodl from a consideration of the following 'detailed description taken in connection with the accompanying drawing forming part of this specification, with the understanding, however, thatthe invention is not confined to any strict conformity with the showingl in the drawing, but may be changed and modified so long as such changes and modiications mark no material departure from the salient features of the invention as ex pressed in the appended claims.

The ligure of drawing is a more or less schematic representation of 4an oil well formed in accordance with the invention'.

In order to convey an idea of the cost and difficulties of drilling an oil well in the Texas field where the oil-bearing sands are from three to four thousand feet -down itis fr' customary to drill a hole which will accommodate from' four to live hundred Afeet of 15% casing, then to sink a hole through the reliminary casing to a depth of a thousanfte twelve hundred feet, to accommodate 1292 casing, to be followed by 1500 to 2000v feetoflO casing, 2500 to 3000 feet ,of 8

easing and finally 3000 to 45000; feet of 6g casing, the different sizes of casing telescoping one into the other and' all reachlng to the surfaceof thev groundl or into a cellar.

The casing necessary for a 4000 foot well, therefore, reaches nearly 11,000 feet or proportionately less, but in any event representing a length of the depth of the well. Moreover such casing is expensive' and the cost of drilling a well may reach from eighty to one hundred thousand dollars on more, and the work often goes for naught. Again, diiliculties are encountered in sinking the casing because of the buckling of the casing, and the sticking of the collars connecting the sections of the casing.

The invention contemplates the formation of a cellar 1, which may be an excavation of suitable diameter to admit workmen and tools, and this excavation may be in the neighborhood of 60 feet in depth. At the bottom of the cellar is a short length of casing surrounded at the bottom end, the casing being upright, by a flooring 3 of cement `or other suitable material so that the casing where passing through the bottom of flooring 3 may make a substantially gas-tight connection therewith. The cellar 1 may be conveniently carried downwardly to the cap rock encountered some distance below the surface of the ground in theTexas formation. The casing 2 is provided at a suit- \able height above the flooring 3 with a cutolfvalve 4 and from thence there is a casing continuation 5 continued to the surface .of the ground through the basic portion 6 of a derrlck 7 The valve 4 is shown as provided with a reach rod 8 so that it may be readily controlled from the surface of the ground.

Leading into the casing 2 is a pipe 9 which may be carried to the surface of the ground and is there connected to an airpump 10 arranged to force the air under cob pressure into the casing 2.

Extending through the casing 2 and its extension 5 is a rope or cable 11'with a walkin beam operating means 12, and at the end of the cable 11 below 'the casing 2 is a drill tool 13, preferably of the ordlnary reciprocatory type and consequently needing no particular description.

When the drilling is begun it may start in the cap .-rock formation indicated at 14 and will then continue downwardly, ultimately reaching the water stratum or sandl indicated at 15.

Ordinarily it is necessary to introduce casing into the bore, which-latter is indicated atv 16, in order to prevent the water frommenterlng the bore. By the present invention the entrance of water into the ore is prevented -by using air pressure in ghe bflre by means of the pump 10 and pipe suc back the water. Ultimately as the drillin proceeds, the water sand is traversed and the drill enters the shale formation undercasing several times that of y sizes of caslng are required and usually air pressure being suiioient'to hold lying the water sand. Such shale formation may be of relatively great depth and ordinarily it has been found necessary to case such formation in order to hold back the shale from caving. However, in accordance with the present invention the shale cannot cave on account of the superior pressure exerted by the air, so that the shale walls of the bore are held against caving as effectively as though a casing were present.

Ultimately the drill reaches the cap rock underlying the caving shale and overlying the as sand and oil. When the cap rock has been traversed and the presence of oil has been ascertained, the drilling tool may be withdrawn and a casing is then introduced, but such casing may be of the same size throughout its length and either of the smallest slze employed or the next larger size. It is necessary to maintain the air pressure within the bore while the casing is being introduced below the water stratum and the cavinfr shale so that there may be no danger o, cavings entering the bore. After this has been accomplished the air pressure may be released and the well bccomesa producing well.

In digging such a well only the smallir on v the smallest size commercially employed. This represents a very material saving in the cost of casing, vwhich usually begins with a 15 or 20 size and is ultimately reduced to 6%. By the invention the size of the casing need not exceed 8 and may be as small as 6g, these being standard sizes.

By the invention the expense of casing,

yand such casing represents a very material outlay of money, is in most part eliminated when, as often occurs, the'boring proves to be futile.

In the ordinary procedure of drilling and casing the drilled hole as the drilling proceeds it sometimes becomes necessary to draw the casing. Occasionally this may be done with considerable ease and ao'ain it cannot be done. In Adeepwells the withdrawing of the easing may result in pulling the casing apart because of the reslstance offered by the pressre of the material which has collapsed against the casing. Under such circumstances the well frequently becomes a total loss and must be abandoned. Should it occur in a well drilled in accordance with this invention that the well must be aban- `doned after the casing has been applied, the

well costs, would, if -the work becomes a loss, represent less than half of the loss incurwith an ordinary drilled well.

n the practice of the invention, it is necessary -from time to time to withdraw the drilln tool and to introduce a bailer or, when t e drilling is finished, to line the ore in some ap ropriate manner to prevent the caving of t e walls of the bore, without material loss ofthe air under pressure employed to sustain the collapsible walls of the bore while the drillin is proceeding, and when the well isfinishe ,introducing a rmanent means for sustaining the'walls o the bore after the temporary air pressure is released.

It is customary in drilling wells to suport the drilling'tools, bailers, etc., on the ower end of wire cables, such as the cable 11, and such cable is passed through a packing head of ordinary construction at the upper end of the short length of casing and so through the cut-off valve 4, sultable packing belng employed at both points. It 1s customa to hold the cap atthe upper end ofthe ength 5 of `casing by screws ory other readily removable means so that when it is desired to remove a drilling tool to replace it 'with a bailer, or to introduce other evices in place lof the drilling tool, such tool or device is raisedA through the valve 4 which is then cut off so as to retain the air pressure, and on the loosening of the fastening devices for the cap, the latter, as well'as the ycable and tool, is lifted from the well. Then another tool or dev1ce, including another cap, is loweredY into the casing extension 5 and the cap is fastened in place, after which the valve 4 may be'opened and the implenient thenlowered into the already-formed well as far as may be desired, the cap preventing the escape of the compressed air holdin the walls o-f the well from collapsing. n this manner, hailing or the sealmg ofthe walls of the well, particularly where collapsible, as through shale or water bearing strata, is readily accomplished without such reduction in air ressure as might permit caving ofthe wa s of the well.

What is claimed is: v

1. The method of ydrilling deep .oil wells, which consists in producing with a drilling tool, a bore in most part of substantially.

which oil is sought, and at the same timeproducing air ressure in the bore asl the sole means for liolding back theA collapsible walls of the bore where such occur, untll the drilling of the collapsible` portions is completed, and then lining the bore with pressure-resistant material.

42. The method of drilling deep oil wells, which consists in producin with a drilling tool, a bore of substantia ly constant d1- ameter down to the formation in which oil is sought, with the bore corres londing in diameter to that standard for t e oil-bearing formations, andxat the same time producing and utilizin air pressure in the bore as the solo means or ho ding-back the collapsible walls of the bore, where they occur,

wherebg' to permit the air pressure to be release 3. The method of forming deep oil wells, which consists in producin with adr-illin tool, a vbore of substantia ly constant d1 ameterdown to the formation in which oil n the bore as the latter progresses, air pressure suiicient lto prevent collapsm ofthe i Walls of the bore where ofl a co lapsible nature, and to hold back flow of water into the bore where passin through water-bean in formations, with t e air pressure `maintained until the productiveness of the well is ascertained, and then providing a lning'for the bore resistant to pressures in and normal to the well tending to collapse the walls of the well, the lining also serving to hold backy the flow of water into the well from water-bearing formations. Y 4 4. The method of drillingV deep oil wells which consists in producing a bore to the formation in which oil is sought, and holding the walls ofthe bore, whilel being,

formed, against collapsing solel by air pressure maintained in the bore uring the drilling operation. A In testimonA hat I claim the foregoing as my own, have hereto ailixed my signature.

WILLIAM E. NOLAN. 

